Load warning device



April 7, 1970 G. H. FATHAUER LOAD WARNING DEVICE 6 Sheets-Sheet 4.

Filed Nov. 13, 1967 INVEN'T01' 266 ,4 Han/4062 wNum QTQN A YQREQQWQ QM wmm mm a 2 Z i ATTQRNEY$ April 1970 G. H. FATHAUER 3,505,514

LOAD WARNING DEVICE Filed Nov. 13, 1967 6 Sheets-Sheet 5 d2 1 INVENTOR.

BY AgJ WATTORNEYS April 1970 f e. H. FATHAUER' 3,505,514

LOAD WARNING DEVICE Filed Nov. 15, 1967 6 Sheets-Sheet 6 INVENTOR.

G k: flan/muse BY @w AJ MATTORNEYS United States Patent 3,505,514 LOADWARNING DEVICE George H. Fathauer, Decatur, Ill., assignor to Eaton Yale& Towne Inc., a corporation of Ohio Filed Nov. 13, 1967, Ser. No.682,387 Int. Cl. G06g 7/22; G08b 21/00 US. Cl. 235-189 2 Claims ABSTRACTOF THE DISCLOSURE FIELD OF THE INVENTION This invention relatesgenerally to a load warning device for a crane and the like and moreparticularly to a warning device which senses both load on the crane andthe angle of the boom and provides an alarm when a predeterminedrelationship of one function exists with re spect to the other functionand is an improvement on my invention disclosed in copendingapplication, Ser. No. 626,563, filed Mar. 28, 1967 entitled Load WarningDevice.

BACKGROUND OF THE INVENTION The safe load capabilities of a crane aredependent upon the strength of the load carrying structures and upon thepoint at which the crane can be tipped. It is readily obvious that theload carrying structures of a crane, such as the hoisting cable, cansupport a predetermined safe load, beyond which point the possibility ofbreakage or damage to the structures can result. In addition, however,and of greater importance, are those conditions which may produce atipping moment and overturn the crane. Tipping of the crane is dependentupon the weight of the load being lifted and the angle of the boom withrespect to a horizontal line. The operator and load tables often convertthe angle of the boom into boom radius which is the horizontal distancefrom the point of attachment of the boom to the lifting hook.

It has been the practice in the past to employ a chart for determiningthe safe load capabilities of a crane with respect to the radius orangle of the boom. An operator of the crane, therefore, must be able tojudge the weight of the load which is to be lifted by the crane and mustalso be able to judge the radius or the angle of the boom with respectto a horizontal line. By comparing the weight of the load to be liftedby the crane and the radius or the angle of the boom on the chart, theoperator can determine if the load exceeds a safe limit. Since theoperators judgment is required to determine the weight of the load andthe radius or angle of the boom, a relatively great probability of errorexists.

One method employed for determining the angle of the crane boom is thatof measuring horizontally from the pivot point of the boom to the loadand either computing mathematically or consulting a graph to find theangle of the boom with respect to a horizontal line. When the angle ofthe crane boom is determined and the weight of the load is either knownor estimated, the operator of the crane must then consult a graph todetermine the safe loading conditions for the crane which will notresult in a tipping of the crane.

A need exists,'therefore, for apparatus which can sense the weight ofthe load being lifted by the crane and the angle of the crane boom andfor computing the product of these two functions to provide a readout ofthe load and radius which will indicate the loading condition of thecrane. Such an apparatus would completely eliminate the human errorwhich presently exists in the determination of the safe load limit for acrane. That is, since it is necessary for an operator to judge theweight of the load to be lifted by the crane and also the radius orangle of the boom with respect to a horizontal line before consultingthe chart to determine if the functions fall within a safe load range,the probability of error resulting from the operators judgment isrelatively great. In addition, the operator is subject to making anerror when reading the chart, further increasing the probability of anerror existmg.

SUMMARY OF THE INVENTION Accordingly, the present invention generallyincludes means for sensing the weight of the load being lifted by thecrane and providing an output indicative thereof, means for sensing theangle of the crane boom and converting this into radius and providing anoutput indicative thereof, and means for computing the product of thetwo outputs and providing a readout indicative of the load capabilitiesof the crane.

It is an object of the present invention to provide a load warningdevice for a crane or the like which automatically senses the weight ofthe load being lifted by the crane and the angle of the crane boom andcomputes the product of these two functions to provide a readoutindicative of the load carrying capabilities of the crane.

A feature of the present invention resides in the provision of means formodifying the computation factors to correct for certain loadlimitations in the crane struc ture as well as for safety factors.

Another feature of the present invention resides in the provision of aplug-in program selector which enables the crane operator to easilyselect computation factors corresponding to the operating conditions ofthe crane.

Still another important feature of the present invention resides in theprovision of a readout calibrated to read the percent of crane capacityso as to assure safe operation of the crane at all times.

Another important feature of the present invention re sides in theprovision of a readout for indicating the weight of the load as well asa readout for indicating the radius of the crane boom.

Another feature of the present invention resides in the provision of aselector switch and a computing circuit for setting the parts of line inthe reeving system of the crane and automatically programming thepercent capacity readout accordingly.

Still another important feature of the present invention resides in theprovision of an automatic alarm system which energizes an external alarmdevice when a predetermined percentage of capacity point is reached.

These and other objects, features and advantages of the presentinvention Will be more fully realized and understood from the followingdetailed description when taken in conjunction with the accompanyingdrawings, wherein:

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a side elevational view ofa crane employing the apparatus of the present invention;

FIGURE 2 is a view in elevation of the components in assembled form ofthe present invention;

FIGURE 3 is a graph of typical loading capabilities of a crane;

FIGURE 4 is a diagrammatic illustration of an angle transducer whichforms a part of the present invention.-

FIGURE 5 is a simplified block diagram of the computer or load warningdevice constructed in accordance with the principles of the presentinvention;

FIGURE 6 is a more detailed block diagram of the system illustrated inFIGURE 5;

FIGURE 7 is a schematic illustration of the input circuit to theoperational amplifiers illustrated in FIG- URE 6;

FIGURE 8 is a schematic diagram of the feedback circuit of anoperational amplifier illustrated in FIG- URE 6;

FIGURES 9-13 are schematic diagrams of the operational amplifiersemployed in the system illustrated in FIGURE 6;

FIGURE 14 is a schematic diagram of the alarm amplifier employed in thesystem illustrated in FIGURE 6; and

FIGURE 15 is a schematic diagram of the voltage regulator controlemployed in the system illustrated in FIGURE 6-.

Like reference numerals throughout the various views of the drawings areintended to designate the same or similar structures.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIGURE 1 illustrates a typicalcrane which is provided with the apparatus of the present invention toprovide a readout of the safe load carrying capabilities thereof. Thecrane includes a cab, generally designated with the reference numeral20, which houses the drive units (not shown) for lifting and moving aload and a control console 21. A boom 22 is pivotally mounted at one endthereof to the cab 20 and supports a tackle assembly 23 at the other endthereof. A cable 24 which is connected to a take-up reel (not shown)within the cab 20 extends to and forms a part of the tackle assembly 23.

The tackle assembly 23 is formed of a pair of pulleys 26 and 27 and ahook 28. The pulley 26 is secured to one end of the boom 22 and the hook28 is connected to the pulley 27. The cable 24 extends over the pulleys26 and 27 to form the tackle assembly 23'. The angle a of the boom 22with respect to a horizontal line is controlled by means of a cable 29secured to the upper end of the boom 22 and connected to another takeupreel (not shown) within the cab 20. The horizontal distance from thepivot point of the boom to the point under the hook is designated at theradius distance r. This distance varies with the cosine of the craneangle a and with the length of the boom L. For a fixed length boom theradius varies from L to zero as the boom is raised from the horizontal.The crane pivot to the boom pivot is a fixed distance added to theradius r. The weight of the load which is to be supported on the book 28is sensed by a load cell 30. An angle transducer 31 is mounted on theboom 22 and senses the angle of the boom 22 with respect to a horizontalline 32. The outputs of the load cell 30 and the angle transducer 31 aresupplied to apparatus in the control console 21 within the cab 20wherein a computation is made therefrom.

FIGURE 2 illustrates the components forming the load warning device ofthe present invention which are adapted for being mounted on theappropriate crane structures. In particular, the load cell 30 is mountedat a point in the load supporting structures so as to sense the weightof the load and the angle transducer 31 is mounted on the boom 22 tosense the angle thereof with respect to a horizontal line. Outputs ofthe load cell 30 and the angle transducer 31 are supplied to a controlunit 33 which contains all of the electronics for performing the desiredcomputations. The load cell 30 is connected to the control unit by meansof a cable 34 and the angle transducer 31 is connected to the controlunit 33 by means of a cable 36. The cables 34 and 36 4 are formed of thenecessary electrical wires for. connecting the load cell 30' and theangle transducer 31 to the control unit 33.

A meter 37 provides a readout of the load being supported on the hook 28and the radius r of the boom 22 as shown in FIGURE 1. A meter 38provides a readout of the crane capacity in percent. The meter 37 isconnected to the control unit 33 by means of an electrical cable 39 andthe meter 38 is connected to the control unit 33 by means of anelectrical cable 40'. The electrical cables 39 and 40 are also formed ofthe wires necessary for interconnecting the respective meters 37, 38with the control unit 33.

The control unit 33 is provided with a front panel 41 having a pluralityof controls mounted thereon. In particular, a control knob 42 controlsthe balance of the load cell 30 output. That is, when there is no loadbeing supported on the hook 28, the meter 37 should indicate a zeroload. A control knob 43 changes a computation factor in accordance withthe number of lines or parts of line of the tackle assembly 23. A 'slot44 is provided in the front panel 41 of the control unit 33 and isdisposed for receiving a program car 82 therein. A control knob 46 isprovided for changing from one program to another program incorporatedin the electronics of the control unit 33. A switch 47 connects power tothe electronics within the control unit 33 and a lamp 48 indicates whensuch power is being applied. A switch 49 is provided for selecting thedesired readout on the meter 37. That is, when the switch is in theposition illustrated in the drawing, the meter 37 will provide a readoutof the radius of the boom 22. However, when the switch 49 is in theopposite position to that illustrated, the meter 37 will provide areadout of the load being supported on the hook 28. A lamp 50 is mountedon the control unit 33 and is actuated when a critical loading point isreached. Each of the control functions provided by the individualcontrols on the unit 33 will be explained in greater detail in thedescription of the electronics hereinbelow.

FIGURE 3 illustrates a graph of boom angle and radius r with respect tothe load. In the past, when an operator of a crane desired to lift aparticular load, it was necessary to consult a chart such as thatillustrated in FIGURE 3 to determine if the crane could support theparticular load at a specified radius or angle of the boom. By findingthe radius or the angle of the boom with respect to a horizontal line onthe axis of abscissas, the operator could find the Weight of the loadwhich the crane could safely support without tipping. The continuouscurve illustrated in FIGURE 3 and designated with the reference numeral51 is a typical curve employed for determining the safe load to besupported by a crane at a particular radius or angle of the boom.

The device of the present invention simulates the curve 51 by developinga plurality of voltages which develop fixed voltage drops across aresistive element. These volt age ditferentials are represented inFIGURE 3 by the straight line sections of a curve 52. By sensing thevoltage developed across the resistive element at a point correspondingto the radius or angle of the boom 22 with respect to the horizontalline 32, the loading conditions can be accurately determined.

FIGURE 4 illustrates one configuration of the angle transducer 31mounted on the born 22. The structure illustrated in FIGURE 4 includes apair of potentiometers 53 and 54 which are connected together by meansof a shaft'56. The potentiometers 53 and 54 are illustratedschematically in FIGURE 6. The housings of the potentiometers 53 and 54are mounted by suitable means (not shown) on the boom 22 of the crane.The shaft56 is secured to the movable contact arm of the potentiometers53 and 54 to rotate the same with respect to the housings thereof. Aportion 57 of the shaft 56 extends from one side of the potentiometer S3and is secured to one end of a lever 58 which supports a mass 59 at theother end thereof. Since the housings of the potentiometers 53 and 54are mounted by suitable means on the boom 22 of the crane, angularmovement of the boom 22 will cause a displacement of the movable contactarm of each of the potentiometers 53 and 54 by virtue of the lever arm58 being maintained in a vertical position.

The potentiometer 53 includes a plurality of terminals 60a-60m and thepotentiometer 54 includes a plurality of terminals 61a-61c. The terminal60a, for example, is electrically connected to the movable contact armof the potentiometer 53 and the terminal 61a, for example, is connectedelectrically to the movable contact arm of the potentiometer 54. Theremaining terminals 60b-60m are electrically connected to taps on theresistance element of the potentiometer 53 and the remaining twoterminals 61b-61c are connected to opposite ends of the resistanceelement of potentiometer 54.

The radius r is the distance point of pivot of the boom on the cranehorizontally to a point directly under the hook 28. This distance r isequal to the boom length L multiplied by the cosine of the angle of theboom a. The resistive element of potentiometer 54 is wound so that theoutput at contact 61a varies as the cosine of the boom angle a and itcan be readily appreciated that by applying a suitable voltage acrossthe resistance element of the potentiometer 54, the voltage on themovable contact arm thereof would be directly proportional to the craneradius r.

In order to simulate the curve 51 illustrated in FIG- URE 3, voltagescorresponding to the ordinates of points 62b-62m on the curve 52 can beapplied to successive and corresponding taps 60b-60m of the resistanceelement of potentiometer 53 and a voltage proportional to the load willbe realized on the movable contact arm of the potentiometer 53. Sincethe movable contact arm of the potentiometer 53 is positioned inaccordance with the boom angle a, the voltage obtained on the movablecontact arm will be proportional to the safe load on the axis ofordinates of the graph illustrated in FIGURE 3. That is, by applyingvoltages to the taps of the potentiometer 53 equal to the ordinates ofthe points 62b-62m of the graph illustrated in FIGURE 3, rotation of themovable contact arm of the potentiometer 53 from one end of theresistance element to the other end thereof would produce a relationshipdepicted by the curve 52 illustrated in FIGURE 3. The boom radius andangle on the axis of abscissas would be represented by the position ofthe movable contact arm and the safe load on the axis of ordinates wouldbe represented by the voltage developed on the movable contact arm. Therespective points 62b-62m would be represented by the voltages appliedto the respective terminals 60b-60m which are connected to respectivetaps on the resistance element of the potentiometer 53. It can bereadily appreciated, therefore, that the device of the present inventionprovides a relative simple structure for simulating a safe load curvefor operation of a crane under safe loading conditions.

FIGURE 5 illustrates a system for producing the voltages to be appliedto the taps 60b-60m on the potentiometer 53 and for producing an alarmwhen the load being supported on the crane is greater than therecommended safe load. In particular, the load cell 30 is supplied withan alternating current voltage from an oscillator 62 and provides anoutput indicative of the load being supported on the crane to anamplifier 63. The load cell 30 is preferably a differential transformerwhich includes a primary winding connected to an output of theoscillator 62, a pair of secondary windings connected in phaseopposition to one another, and a movable slug disposed for supporting aweight thereon which is to be measured and for changing the couplingbetween the primary winding and the secondary windings. At no loadconditions, the coupling to the secondary windings is preferably equal.When the slug is moved under the influence of a weight thereon, thecoupling from the primary winding to one of the secondary windings isreduced and the coupling to the other secondary winding is increased. Asa result of this change in the coupling, a signal is provided at anoutput of the load cell 30, the amplitude of which is proportional tothe weight supported on the slug. The differential transformer load cellis well known in the art. It is to be understood, however, that othertypes of load cells may also be employed in the practice of the presentinvention. The amplifier 63 is provided with a feedback resistance 64and phase correction for the load cell 30 is provided by a circuit 66.The output of the amplifier 63 is supplied to a demodulator 67 whereinthe signal is rectified.

One output of the demodulator 67 is supplied to the readout 37 forproviding an indication of the load being supported on the load cell 30.Another output of the demodulator 67 is supplied to a function generator68 wherein the voltages which are to be supplied to the angle transducer31 are produced. The angle transducer 31 supplies a signal to thereadout 37 for providing an indication of the radius of the boom 22. Anoutput of the function generator 68 is supplied through an amplifier 69to an alarm 70 which indicates an unsafe loading condition for aparticular load being supported and for a particular radius of the boom.

It will be noted from FIGURE 1 that the load cell 30 is mounted at apoint in the load supporting structures of the crane to receive theentire weight of the load thereon. It may be desirable, however, toposition the load cell 30 at a point in the load supporting structuresso that only a fractional portion of the weight of the load is realizedthereby. For instance, the load cell 30 can be connected in the cable24, such as by cutting the cable 24 and securing the cut ends toopposite sides of the load cell 30. In such an instance, however, theoutput of the load cell would be equal to the load supported on thecrane 28 multiplied by the number of lines in the tackle assembly 23.Since it is possible for the tackle assembly to be changed by providinga greater or a lesser number of lines therein, a circuit 71 is providedbetween the function generator 68 and the amplifier 69 for providingsuch a multiplication. It is to be understood that the load cell 30 canalso be positioned to sense the tension in the cable 24, if desired, orany suitable installation can be provided which will provide an outputindicative of the load being supported by the crane.

The block diagram of FIGURE 5 is illustrated in more detail in FIGURE 6.As shown therein, the function generator 68 is connected to an output ofthe demodulator 67 through a resistor 72. The input to the functiongenerator 68 is connected to one input of an operational amplifier 73. Afeedback circuit 74 is connected between an output of the amplifier 73and an input thereof. The feedback circuit 74 is illustrated in FIGURE 7and generally includes a selector switch 76 having a movable contact arm77 which is disposed for connecting one of a plurality of resistors 78between a terminal 79 and a terminal 80. In addition, the movablecontact arm 77 is disposed for connecting the terminal 79 directly to aterminal 81. The terminal 79 of the feedback circuit 74 is connected toan input of the amplifier 73 and the terminal 80 is connected to anoutput thereof.

In essence, the selector switch 76 selects one of the resistors 78 to beconnected between the output and the input of the amplifier 73.Therefore, the selector switph 76 performs the function of a multiplier.

A program card, generally designated with the reference numeral 82, isdisposed for being received in the slot 44 in the front panel 41 of thecontrol unit 33 and includes a resistor 83 thereon. When the programcard 82 is inserted into the slot 44, the resistor 83 is connectedbetween the terminal 80 and the terminal 81 of the selector switch 76.Therefore, when the movable contact 77 of the selector switch 76 is inthe position illustrated in the drawing, the resistor 83 forms thefeedback circuit for the amplifier 73. It can be readily appreciatedthat the program of the device of the present invention can be alteredeither by the selector switch 76 or by insertion of the program card 82into the slot 44 of the control unit 33.

The operational amplifier 73 provides an output on a line 84 which issupplied to an input of a plurality of operational amplifiers 86-94through a respective selector switch 75a-75j. The operational amplifiers88-93 are omitted from the drawing for simplicity of illustration andare represented by the dot-dash line designated 88-93. The selectorswitches 75a-75j are connected between the output of the operationalamplifier 73 on the line 84 and one input of the operational amplifiers86-94 and are disposed for connecting a predetermined value ofresistance therebetween. In addition, the program card includes aplurality of resistors 96-104 which may be connected by the selectorswitches 7511-751 between an output of the operational amplifier 73 anda respective input of the operational amplifiers 86-94. The dot-dashlines in the drawing indicate the omission of parts from the drawing forpurposes of simplicity of illustration. Each of the operationalamplifiers 86-94 are provided with a feedback resistance 106-114.

Outputs of the amplifiers 86-94 are connected to the terminals 60b-60kof the potentiometer 53. As previously discussed, an output of each ofthe amplifiers 86-94 corresponds to the ordinate of a correspondingpoint 62b-62m on the curve 52 illustrated in FIGURE .3. The voltageoutputs of the amplifiers 86-94 can be varied individually by changingthe input resistance to each of the amplifiers. As previously mentioned,the input resistance to each of the amplifiers 86-94 is selected byoperation of the selector switches 7Sa-75j. The outputs of all of theamplifiers 86-94 can be changed collectively by the selector switch 74connected in the feedback circuit of the amplifier 73. Each of theswitches 74 and 75a-75j are ganged together so as to providecontinuously increasing voltage steps of the potentiometer 53. In thismanner, voltage increments are produced which will simulate variouscurves, such as the curve 52 illustrated in FIGURE 3. By positioning theswitches 74 and 75a-75j such that electrical contact is effected betweenthe terminals 79 and 81, the resistor 83 of the program card 82 will beconnected into the feedback path of the amplifier 73 and the resistors96-104 of the program card 82 will be connected as input resistors tothe amplifiers 86-94 respectively. Therefore, if the desired programcannot be established by proper selection of the switches 74 and75a-75j, an appropriate program card 82 can be fabricated having thedesired resistance values for the resistors 83 and 96-104.

The lever 58 illustrated in FIGURE 4 which is secured to the shaft 57 ofthe otentiometers 53 and 54 is illustrated diagrammatically in FIGURE 6by the dashed line designated with the numeral 58. The movable contactarms of the potentiometers 53 and 54 are positioned in accordance withthe angle of the boom with respect to a horizontal line. The terminals61b and 61c of the potentiometer 54 are connected to suitable voltages Vand V respectively. The voltage realized on the movable contact arm ofthe potentiometer 54, therefore, is proportional to the radius r of theboom. The movable contact arm of the potentiometer 54 is connected to aninput of an amplifier 116.

An output of the operational amplifier 116 is connected to the meter 37through a switch 117 to provile a readout of the radius r of the boom.An output of the demodulator 67 is also connected through the switch 117to the meter 37 to provide a readout of the load being supported on thecrane. Therefore, when the switch 117 is in the position as illustratedin the drawing, a readout of the radius of the boom is provided and whenthe switch 117 is in the opposite position to that illustrated in thedrawing, a readout of the load being supported by the crane is indicatedon the meter 37.

The movable contact arm of the potentiometer 53 is connected to oneinput of an amplifier 118 having a feedback circuit generally designatedwith the reference numeral 119.

The feedback circuit 119 is illustrated in FIGURE 8 and includes aselector switch 120 having a movable contact arm 121. The movablecontact arm 121 is connected to a terminal 122 which is, in turn,connected to an input of the amplifier 118. A terminal 123 is connectedto the fixed contacts of the selector switch 120 to a series toresistors 124. The terminal 123 is connected to an output of theamplifier 118. By changing the position of the movable contact arm 121of the selector switch 120, the resistance of the feedback circuit forthe amplifier 118 is altered. This change in the feedback resistanceelfects a multiplication of the output of the amplifier 118. Thismultiplication factor is related to the parts of line in the tackleassembly 23.

As previously mentioned, the voltage developed on the movable contactarm of the potentiometer 53 is proportional to the capacity of the cranewith respect to the load being lifted. The output of the amplifier 118is connected through a resistor 126 to the meter 38 to provide a readoutof the crane capacity in percent. The output of the amplifier 118 isalso connected through the alarm amplifier 69 to the base of atransistor 127. The transistor 127 is connected between a source ofunregulated voltage V and the alarm device 70. Consequently, if thevoltage realized by the movable contact arm of the potentiometer 53exceeds a predetermined limit, an alarm will be provided by the device70.

The voltage V is connected to an input of a voltage regulator 128 whichdevelops a regulated voltage V on an outputline 129. Another output ofthe voltage regulator 128 is connected to the base of a transistor 130.The emitter of the transistor 130 is connected to the voltage V and aregulated output voltage V is developed at the collector thereof.

FIGURE 9 illustrates a schematic diagram of the operational amplifier63. A terminal 131 forms an input to the amplifier and a terminal 132forms an output thereof. The feedback resistor 64 is connected betweenthe terminals 131 and 132 and forms a feedback circuit for theamplifier.

The operational amplifier 63 includes a pair of tran sistors 133 and 134having their emitters connected together through a resistance 136 toground potential. The input terminal 131 is connected to the base of thetransistor 133 and the voltage source V is connected to the base of thetransistor 133 through a resistor 137. The collector of the transistor133 is connected to the voltage source V Any variation in the inputsignal on the terminal 131 will alter the conduction of the transistor133 to change the potential applied to the emitter of transistor 134.The base of the transistor 134 is connected to the voltage source V and,therefore, the transistor 134 is biased by the voltage at the emitterthereof. The collector of the transistor 134 is connected through aresistance 138 to the voltage V; and to the base of a transistor 139.The signal which is amplified by the transistor 134 is applied to thebase of the transistor 139 for further amplification thereof.

The emitter of the transistor 139 is connected to the voltage V and theemitter thereof is connected through a resistance 140 to groundpotential and a capacitor 141 to the base thereof. The amplified signalat the collector of the transistor 139 is supplied to the base of atransistor 142 having the collector thereof connected to the voltage VThe emitter of the transistor 142 is connected to the output terminal132 and through a resistance 143 to ground potential. This arrangementprovides a relatively large amplification factor. The signal developedat the output terminal 132 is fed back through the resistor 64 to theinput terminal 131. If an input signal is supplied to the terminal 131,the output will attain a value which will provide through the resistor64 a nullification of the input signal at the base of the transistor133. Any increase in the input signal, therefore, will cause the outputfrom the amplifier 63 to increase.

FIGURE illustrates a schematic diagram of the operational amplifier 73.Since the amplifier 73 is substantially identical to the amplifier 63illustrated in FIG- URE 9, the correspondingly similar components havebeen designated with the same reference numeral. In the amplifier 73,the base of the transistor 133 is connected solely through a resistor144 to the input terminal 131. In addition, the base of the transistor134 is connected through a resistor 146 to the voltage source V Thefeedback circuit for the amplifier 73 is formed of the resistancenetwork and switch illustrated in FIGURE 7 or the resistor 83 on theprogram card 82. This feedback arrangement is illustrated in FIGURE 6 ofthe drawings.

FIGURE 11 illustrates a schematic diagram of the operational amplifiers86-94. Each of the operational amplifiers 8694 are also similar to theamplifier 63 illustrated in FIGURE 9 and, consequently, thecorrespondingly similar components thereof have been designated with thesame reference numeral. The output terminal 132 of the amplifier 73illustrated in FIGURE 10 is connected to a respective one of the inputterminals 131 of the amplifiers 8694 illustrated in FIGURE 11 throughthe resistance network and switch of FIGURE 7 or through a respectiveone of the resistances 96-104 on the program card 82.

FIGURE 12 illustrates a schematic diagram of the operational amplifier118. A terminal 147 forms a feedback input to the amplifier and aterminal 148 forms an output thereof. The feedback circuit illustratedin FIG- URE 8 is connected between the terminals 147 and 148. Theterminal 147 is connected to the base of a transistor 149 having thecollector thereof connected to the voltage V The emitter of thetransistor 149 is connected in common with the emitter of a transistor150 and through a resistor 151 to ground potential. A terminal 152 formsa signal input to the amplifier 118 and is connected to the base of thetransistor 150 and through a capacitor 153 to ground potential. Thecollector of the transistor 150 is connected to the voltage V through aresistor 154.

The conduction level of the transistor 149 is dependent upon the signalwhich is supplied from the output termi nal 148 and through the feedbackcircuit illustrated in FIGURE 8 to the base thereof. The conductionlevel of the transistor 149 determines the potential at the emitter ofthe transistor 150, which transistor is disposed for amplifying theinput signal applied to the base thereof. Consequently, as the potentialat the emitter of the transistor 150 is varied, the amplification of thesignal at the input terminal 152 will also vary. The feedback circuitfor the amplifier 118 is employed for changing the amplification factorof the amplifier in accordance with the number of lines in the tackleassembly 23 of the crane.

The amplified signal at the collector of the transistor 150 is suppliedto the base of a transistor 156. The emitter of the transistor 156 isconnected to the voltage V and the collector thereof is connectedthrough a resistor 157 to ground potential and through a capacitor 158to the base. The amplified signal at the collector of the transistor 156is supplied to the base of a transistor 159. The collector of thetransistor 159 is connected to the voltoge V and the emitter thereof isconnected to the output terminal 148 and through a resistor 160 toground potential. The voltage V is connected through a diode 161 to theoutput terminal 148. If the voltage V is positive, the cathode of thediode 161 is connected to the output terminal 148.

FIGURE 13 illustrates a schematic diagram of the operational amplifier116. A terminal 162 forms an input to the amplifier and a terminal 163forms an output thereof. The collector of the transistor 164 isconnected to the voltage V and the emitter thereof is connected incommon to the emitter of a transistor 166 and through a resistor 167 toground potential. The input terminal 162 is connected to the base of thetransistor 166 and through a capacitor 168 to ground potential. Afeedback resistor 169 is connected between an output of the amplifier116 and the base of the transistor 164. The feedback signal through theresistor 169 determines the conduction level of the transistor 164 andthe potential developed at the emitter of the transistor 166.Consequently, amplification of an input signal on the input terminal 162by the transistor 166 will be dependent upon the feedback signal throughthe feedback resistor 169. The collector of the transistor 166 isconnected through a resistor 170 to the voltage V and also to the baseof a transistor 171. The emitter of the transistor 171 is connected tothe voltage V The collector of the transistor 171 is connected through aresistor 172 to ground potential and through a capacitor 173 to the basethereof. The signal which is amplified by the transistor 171 is suppliedto the base of a transistor 174. The collector of the transistor 174 isconnected to the voltage V and the emitter thereof is connected througha resistor 176 to ground potential. The emitter of the transistor 174 isconnected through a calibration resistance 177 which is engaged by wipercontact 211. A shaft 212 with a knob 213 is attached to contact 211. Aresistor 178 is connected between Wiper contact 211 and output terminal163. Knob 213 may be used to adjust the system for booms of varyinglengths. The feedback resistor 169 is connected between the emitter ofthe transistor 174 and the base of the transistor 164.

FIGURE 14 illustrates a schematic diagram of the alarm amplifier 69. Aterminal 179 forms an input to the amplifier and a terminal 180 forms anoutput thereof. The input terminal 179 is connected to the base of atransistor 181 and through a capacitor 182 to the base of a transistor183. The base of the transistor 183 is connected to the variable contactarm of a potentiometer 184 which is connected in series with a pair ofresistors 186 and 187 between the voltages V and V The collector of thetransistor 183 is connected to the voltage V and the emitter thereof isconnected in common with the emitter of the transistor 181 and through aresistor 188 to ground potential.

The conduction level of the transistor 183 is determined by the positionof the contact arm of the potentiometer 184 and determines the potentialdeveloped at the emitter of the transistor 181. An input signal appliedto the input terminal 179 is amplified by the transistor 181 at thecollector thereof, which amplification is dependent upon the potentialat the emitter of the transistor 181. The collector of the transistor181 is connected through a resistor 189 to the voltage V and to the baseof a transistor 190. The emitter of the transistor 190 is connected tothe voltage V and the collector thereof is connected through a capacitor191 to the base thereof and through a resistor 192 to ground potential.The collector of the transistor 190 forms an output of the amplifier 69.

FIGURE 15 illustrates a schematic diagram of the voltage regulator 128which develops the regulated voltages V and V from an unregulatedvoltage supply V The voltage V is connected to the emitter of thetransistor 130 and the voltage V is developed at the collector thereof.The conduction level of the transistor 130 determines the value of thevoltage V which conduction level is established by the voltage appliedto the base of the transistor 130. The collector of the transistor 130is connected to the emitter through a resistor 193 and is furtherconnected to ground potential through a capacitor 194. The voltage V isconnected to the base of the transistor 130 and the emitter of thetransistor 196 through a resistor 197. The voltage V is also connectedto the base of the transistor 196 through a resistor 198. The collectorof the transistor 196 is connected through a resistor 199 to groundpotential. The potential developed at the base of the transistor 130 isdependent upon the conduction level of the transistor 196, which is inturn, dependent upon the conduction level of a transistor 200. Thecollector of the transistor 200 is connected to the base of thetransistor 196 and also through a capacitor 201 to ground potential. Thebase of the transistor 200 is connected to the voltage V, which isdeveloped across a network including a resistor 202 and a Zener diode203 connected in series between the voltage V and ground potential. Theconduction level of the transistor 200 is determined by the potentialapplied to the emitter thereof which is connected in common with theemitter of a transistor 204 and is also connected through a resistor 206to ground potential. The collector of the transistor 204 is'connected tothe voltage V and the base thereof is connected to the movable contactarm of a potentiometer 207 which is connected in series with a pair ofresistors 208 and 209 between the voltage V and ground potential. Thebase of transistor 204 is also connected through a capacitor 210 to thevoltage V The C H- duction level of the transistor 204, which determinesthe potential developed at the emitter of the transistor 200, isdetermined by the position of the movable contact arm of thepotentiometer 207. Therefore, the voltage V can be adjusted byadjustment of the movable contact arm of the potentiometer 207. Thevoltage V is fixed, since it is equal to the Zener breakdown voltage ofthe Zener diode 203.

The principles of the invention explained in connection with thespecific exemplifications thereof will suggest many other applicationsand modifications of the same.

The invention claimed is:

1. A loading indicator for a crane having a boom for supporting a loadcomprising (a) means responsive to the load on the crane, (b) meanscalculating the projected radius r of the free end of the boom from itspivot point and including a first potentiometer mounted on the boom andhaving a winding which is wound so that its electrical resistance variesas a function of the cosine of the angle of the boom with the horizontaland has a wiper contact, a pendulum contacted to said wiper contact tomove it as the radius r is changed, an indicator connected to said wipercontact to indicate the radius r of the boom, and (c) combining meanscomprising a second potentiometer with a wiper contact connected to saidpendulum and having a plurality of tap points corresponding to boomradii, a plurality of load and radius circuits each receiving inputsfrom said means responsive to the load and producing outputs indicativeof safe loads of the crane for particular boom radius and connected tosaid tap points on said second potentiometer corresponding to the boomradius, and a warning device connected to the wiper contact of saidsecond potentiometer to indicate a unsafe condition.

2. A loading indicator according to claim 1 comprising a secondindicator connected to said wiper contact of said second potentiometerto indicate percentage of crane capacity.

References Cited UNITED STATES PATENTS 2,330,060 9/1943 Kuehni340---26-7 2,418,576 4/ 1947 Conrad 340267 2,772,411 11/ 6 Cooper 3402822,858,070 10/1958 Scharff 235-61 3,079,080 2/ 7963 Mason 23 5-l513,262,022 1/1968 Mork et a1. 340276 FOREIGN PATENTS 815,591 7/ 1959Great Britain. 1,157,464- 5/1958 France.

MALCOLM A. MORRISON, Primary Examiner R. W. WEIG, Assistant Examiner US.Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 505,514: D d April 7, 1970 Inventor(s) GEORGE H. FATHAUER It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 4, line 64, "bom 22" should read -boom 22-.

Column 7, line 66, "provile" should read provide.

Column 12, line 2, "contacted" should read -connected-.

Signed and sealed this 3rd day of August 1971 (SEAL) Attest:

EDWARD M .FIETCHER,JB. WILLIAM E. SCH'UYLER, JR. Attesting OfficerCommissioner of Patents

